1. Field of the Invention
The present invention relates to a process for fixing a toner image and a fixing agent composition therefor, and more particularly, to a process for fixing a toner image formed by electrophotography, electrostatic printing, magnetic printing or adherography, of fixing a toner image transferred to a transferring member, and a fixing agent composition therefor.
2. Description of the Prior Art
Heretofore, it has been known that toner images are produced by various image forming methods and, if desired, are transferred to a final image supporting member and fixed. The toners used here are, in general, finely divided powders composed of a mixture of a thermoplastic resin and a coloring matter, and the toners give toner images by a dry type or wet type developing method. The resulting toner image can be everlastingly fixed onto a supporting member by melting or dissolving the toner using heat, pressure or a solvent vapor.
Fixation by using a solvent vapor is disclosed in U.S. Pat. No. 2,776,907 and is more efficient than heat fixation, but the solvent vapor contaminates the air, that is, there is a problem from a hygienic point of view. Therefore, heat fixation is widely used for fixing toner images. Heat fixation should be effected at a temperature lower than the heat degradation temperature of the support such as paper, and for the purpose of completely fixing toners at a high fixing speed, toners of a low fusing temperature should be used. However, toners of a low fusing temperature tend to agglomerate during use and storage and cause blocking phenomenon.
High speed copiers have been recently used and there is employed a fixing method using heat rollers capable of giving a high efficiency of heat transfer, for example, as disclosed in U.S. Pat. Nos. 3,108,863; 3,612,820; 3,649,992; and 3,743,403. Toners used in said mixing methods should satisfy the conditions as to fusing temperature as mentioned above and furthermore, should be of a good releasability free from offset on a heat roller. A material capable of enhancing releasability of toners often causes blocking phenomenon. Therefore, it is difficult to select proper toner materials, and improved toners free from the above mentioned disadvantages are more expensive than conventional ones.
Fixation of toners by pressure is disclosed in, for example, U.S. Pat. No. 3,269,626 and can be effected with only a small amount of energy, and furthermore, an instant starting and high speed fixation can be effected. However, it is complicated to produce a pressure sensitive toner and a toner having a pressure sensitivity and the general characteristics required for toners are usually complicated in its composition and are expensive. Thus, pressure fixation is not yet so widely employed.
In view of the foregoing, toners satisfying chargeability, storage stability, durability, transferability as well as fixability are obtained with difficulty because materials satisfying all of these characteristics are hardly found and the process for preparing such toner is usually very complicated and the resulting toner becomes expensive.
Materials for improving fixability of toners usually have adverse effects on various characteristics required for toners other than fixability and therefore, have not been used. These situations hinder providing a high speed fixation with a reasonable toner. Further it has been proposed to provide preliminarily the whole surface of a support with a fixing agent, but this treatment soils the support and the support thus treated is not inscribable.